Scientific tests have confirmed that human remains found in Russia last year belong to two children of the last Tsar executed by a Bolshevik firing squad in 1918, Russian officials said on Wednesday.

"We received full confirmation that they (the remains) do belong to the Tsar's children," Eduard Rossel, governor of the Sverdlovsk region where the imperial family was killed, said in comments broadcast by Russia's NTV television station.

"So we have found the whole family," he said, adding the tests were conducted in a U.S. genetic science laboratory.

Bolshevik revolutionaries shot the family in the basement of a merchant's house in the city of Yekaterinburg, 1,450 km (900 miles) east of Moscow.

Attempts were made to destroy the bodies, then they were dumped into pits. Following the collapse of Communist rule, remains believed to belong to the Tsar, his wife and three daughters were exhumed. They were reburied in 1998 in the imperial crypt of St Peter and Paul Cathedral in St Petersburg.

But Prince Alexei Nikolayevich and Grand Duchess Maria Nikolayevna were not among those remains. Scientists, prosecutors and amateur historians have mounted a huge operation to find them while some speculated they might have survived.